Switchboard jack and plug.



A. LARSSON. SWITGHBOARD JACK AND PLUG.

APPLICATION FILED APR. 23, 1909.

Patented Feb.22,1910.

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UNITED STATES PATENT OFFICE.

ALFREDLARSSON, OF STOOKHOLM, SWEDEN, ASSIGNOR TO L. 3'1. ERICSSONTELEPHONE MANUFACTURING COMPANY, OF BUFFALO, NEW YORK, A CORPORATION OFNEW YORK.

SWITCHBOARD JACK AND PLUG.

Patented Feb. 22, 1910.

Application filed April 23, 1909. Serial No. 491,752.

To all whom it may concern:

Be it known that I, ALFRED LARSSON, a subject of the King of Sweden,residing at Stockholm, Sweden, have invented a new and usefulImprovement in Switchboard Jacks and Plugs, of which the following is aspecification.

This invention relates to an improved jack and plug designed moreparticularly for telephone switch-boards. Its object is to so constructthe jack and plug that the jacksprings cannot come in contact with anyof the plug-sleeves except those with which they are intended to makeconnection when the plug is fully inserted, in order to preventshort-circuiting of the springs or the plug conductors.

In the accompanying drawings: Figure 1 is a top plan view of theimproved jack, with the plug removed and the springs in normal position.Fig. 2 is a. similar view of the jack and plug showing the latter partlyinserted. Fig. 3 is a similar view showing the plug fully inserted.

Similar letters of reference indicate corresponding parts in the views.

A and B indicate the fixed front and rear bars of the jack-strip of aswitch-board. The particular jack shown comprises a pair of innersprings a, 6 having the usual contact points; a pair of opposing outersprings 0, (Z of diiferent lengths cooperating therewith, and an outerspring 6 longer than the last-named springs and resting normally againstan insulated stop pin f.

9 indicates the customary jack-base or bushing seated in the front bar Aand adapted to receive a corresponding plug H.

The several jack-springs 0, (Z and e are provided on their inner sideswith salient contact-faces 0 (Z and 6 respectively, each of a differentlength or dimension from the contact faces of the remaining springs. Inthe construction shown, the contact faces of the several springsprogressively increase in length toward the front of the jack.

The plug H has a number of contact sleeves 72 it, 71. corresponding tothe number of movable jack springs, which is three in the example hereinshown. The tapering tip 27 of the plug is of ivory or other suitablenon-conductive material and its contact sleeves are separated bysuitable insulators i '5 these insulators and the base or largestportion of the tip being raised above the surface of said sleeves, asshown. The several sleeves progressively diminish in length toward thetip to correspond to the respective contact faces 0 (Z 0" of thejacksprings, but the face of the front spring 0 is longer than theintermediate plug-sleeves it, 7L and the face of the intermediate spring(Z is longer than the front plug-sleeve /i, so that when, in insertingthe plug, a given sleeve thereof comes opposite a contact face of ajack-spring other than its companion, said face will bridge the raisedinsulators on opposite sides of said sleeve and remain out of contactwith the latter. In other words, the contact-face of each spring islonger than the plug-sleeve or sleeves in advance of the sleeve withwhich that face cooperates. By reference to Fig. 2 which shows the plugpartly inserted, it will be observed that the contact face of theintermediate spring 625 bridges the front sleeve 7L, and the contactface of theforemost spring 0 bridges the intermediate sleeve h Vhen,however, the plug is fully inserted, as shown in Fig. 3, the sleevescome opposite the contact-faces of the respective jack-springs and clearthe insulators, permitting them to make connection with the companionsprings and establishing the desired circuits.

It will be seen from the foregoing that inasmuch as none of theplug-sleeves can contact with any of the jack-springs unless the plug isfully inserted, all liability of short-circuiting the springs or theconductors of the plug is effectually obviated. The usualplug-conductors may be connected with the corresponding sleeves in anysuit able or well known manner. They form no partof the invention andare nottherefore illustrated in the drawings.

I do not wish to be confined to the particular embodiment of theinvention herein shown and described as various changes in theconstruction of the parts may be made within the scope of the appendedclaims, and the number and arrangement of the jacksprings may obviouslybe varied to suit clifferent telephone systems or circuit requirements.

I claim as my invention:

1. The combination of the jack-springs having contact faces, and acooperating plug having contacts corresponding to the respectivespring-faces and intervening insulators raised above said plug-contacts,the plugcontacts diminishing in length toward the front of the plug andthe contact-face of each spring being longer than the plug-contact orcontacts in advance of its companion plug-contact.

2. The combination of the jack-springs having contact faces whichprogressively increase in length toward the front of the jack, and aplug having corresponding contacts which progressively diminish inlength toward the front of the plue'.

The combination of the jack-springs having contact-faces and acooperating plug having a non-conductive tip and contact sleevescorresponding to the respective spring-faces and progressivelydiminishing in length toward said tip and insulators separating saidsleeves and 'ais d above the surface thereof, the contact-face of eachspring being longer than the plug-sleeve or sleeves in advance of itscompanion sleeve.

a. A switch-board jack comprising a number of springs adapted tocooperate with cor- 5 responding contact sleeves of a plu the in lengthfrom the faces of the other springs of the jack.

5. A switch-board jack having springs each provided with a salientcontact face,

ALFRED LiiRSSON.

lVitnesses CARL FRIBERG, Human Pn'r'rnnsorr.

salient contact-face of each spring differing the contact faces of theseveral springs in-

